1 // SPDX-License-Identifier: GPL-2.0-only 1 // SPDX-License-Identifier: GPL-2.0-only
2 /* 2 /*
3 * Copyright (c) 2021, Microsoft Corporation. 3 * Copyright (c) 2021, Microsoft Corporation.
4 * 4 *
5 * Authors: 5 * Authors:
6 * Beau Belgrave <beaub@linux.microsoft.com> 6 * Beau Belgrave <beaub@linux.microsoft.com>
7 */ 7 */
8 8
9 #include <errno.h> 9 #include <errno.h>
10 #include <sys/ioctl.h> 10 #include <sys/ioctl.h>
11 #include <sys/mman.h> 11 #include <sys/mman.h>
12 #include <sys/uio.h> <<
13 #include <fcntl.h> 12 #include <fcntl.h>
14 #include <stdio.h> 13 #include <stdio.h>
15 #include <unistd.h> 14 #include <unistd.h>
16 #include <linux/user_events.h> 15 #include <linux/user_events.h>
17 16
18 const char *data_file = "/sys/kernel/tracing/u !! 17 /* Assumes debugfs is mounted */
19 int enabled = 0; !! 18 const char *data_file = "/sys/kernel/debug/tracing/user_events_data";
>> 19 const char *status_file = "/sys/kernel/debug/tracing/user_events_status";
20 20
21 static int event_reg(int fd, const char *comma !! 21 static int event_status(char **status)
>> 22 {
>> 23 int fd = open(status_file, O_RDONLY);
>> 24
>> 25 *status = mmap(NULL, sysconf(_SC_PAGESIZE), PROT_READ,
>> 26 MAP_SHARED, fd, 0);
>> 27
>> 28 close(fd);
>> 29
>> 30 if (*status == MAP_FAILED)
>> 31 return -1;
>> 32
>> 33 return 0;
>> 34 }
>> 35
>> 36 static int event_reg(int fd, const char *command, int *status, int *write)
22 { 37 {
23 struct user_reg reg = {0}; 38 struct user_reg reg = {0};
24 39
25 reg.size = sizeof(reg); 40 reg.size = sizeof(reg);
26 reg.enable_bit = 31; <<
27 reg.enable_size = sizeof(*enabled); <<
28 reg.enable_addr = (__u64)enabled; <<
29 reg.name_args = (__u64)command; 41 reg.name_args = (__u64)command;
30 42
31 if (ioctl(fd, DIAG_IOCSREG, ®) == - 43 if (ioctl(fd, DIAG_IOCSREG, ®) == -1)
32 return -1; 44 return -1;
33 45
>> 46 *status = reg.status_index;
34 *write = reg.write_index; 47 *write = reg.write_index;
35 48
36 return 0; 49 return 0;
37 } 50 }
38 51
39 int main(int argc, char **argv) 52 int main(int argc, char **argv)
40 { 53 {
41 int data_fd, write; !! 54 int data_fd, status, write;
>> 55 char *status_page;
42 struct iovec io[2]; 56 struct iovec io[2];
43 __u32 count = 0; 57 __u32 count = 0;
44 58
>> 59 if (event_status(&status_page) == -1)
>> 60 return errno;
>> 61
45 data_fd = open(data_file, O_RDWR); 62 data_fd = open(data_file, O_RDWR);
46 63
47 if (event_reg(data_fd, "test u32 count !! 64 if (event_reg(data_fd, "test u32 count", &status, &write) == -1)
48 return errno; 65 return errno;
49 66
50 /* Setup iovec */ 67 /* Setup iovec */
51 io[0].iov_base = &write; 68 io[0].iov_base = &write;
52 io[0].iov_len = sizeof(write); 69 io[0].iov_len = sizeof(write);
53 io[1].iov_base = &count; 70 io[1].iov_base = &count;
54 io[1].iov_len = sizeof(count); 71 io[1].iov_len = sizeof(count);
>> 72
55 ask: 73 ask:
56 printf("Press enter to check status... 74 printf("Press enter to check status...\n");
57 getchar(); 75 getchar();
58 76
59 /* Check if anyone is listening */ 77 /* Check if anyone is listening */
60 if (enabled) { !! 78 if (status_page[status]) {
61 /* Yep, trace out our data */ 79 /* Yep, trace out our data */
62 writev(data_fd, (const struct 80 writev(data_fd, (const struct iovec *)io, 2);
63 81
64 /* Increase the count */ 82 /* Increase the count */
65 count++; 83 count++;
66 84
67 printf("Something was attached 85 printf("Something was attached, wrote data\n");
68 } 86 }
69 87
70 goto ask; 88 goto ask;
71 89
72 return 0; 90 return 0;
73 } 91 }
74 92
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